[lmi-commits] [lmi] master 327cb78 1/2: Allow printing illustrations that lapse in first year

[Greg Chicares]

branch: master
commit 327cb7857de3c1ab08694e140ff212effbe35bdf
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Allow printing illustrations that lapse in first year
    
    If this threw an exception, and every 1000th cell in a 10000-cell group
    lapsed in the first year, then the end user would have to run the case
    ten times, producing 999, 1999, ... 9999, 10000 PDFs on successive time-
    consuming runs and editing the census by hand after each failure.
---
 miscellany.cpp      | 12 ++++++++----
 miscellany_test.cpp |  7 ++++---
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/miscellany.cpp b/miscellany.cpp
index 1125b13..e21af0d 100644
--- a/miscellany.cpp
+++ b/miscellany.cpp
@@ -295,7 +295,7 @@ std::string iso_8601_datestamp_terse()
 /// Compute the number of pages needed to display the given number of non-blank
 /// rows in groups of the specified size separated by blank rows.
 ///
-/// Preconditions: 0 < total_rows && 0 < rows_per_group <= rows_per_page
+/// Preconditions: 0 <= total_rows && 0 < rows_per_group <= rows_per_page
 
 int page_count
     (int total_rows
@@ -303,9 +303,13 @@ int page_count
     ,int rows_per_page
     )
 {
-    LMI_ASSERT(0 < total_rows);
-    LMI_ASSERT(0 < rows_per_group                 );
-    LMI_ASSERT(    rows_per_group <= rows_per_page);
+    LMI_ASSERT(0 <= total_rows);
+    LMI_ASSERT(0 <  rows_per_group                 );
+    LMI_ASSERT(     rows_per_group <= rows_per_page);
+
+    // If there are zero rows of data, then one empty page is wanted.
+    if(0 == total_rows)
+        return 1;
 
     // Each group actually takes rows_per_group+1 rows because of the
     // separator row between groups, hence the second +1, but there is no
diff --git a/miscellany_test.cpp b/miscellany_test.cpp
index 8f04677..eaafa73 100644
--- a/miscellany_test.cpp
+++ b/miscellany_test.cpp
@@ -156,7 +156,8 @@ void test_page_count()
 {
     // Original tests: vary only the number of data rows.
 
-    // Edge case (0 rows is not allowed).
+    // Edge cases.
+    BOOST_TEST_EQUAL(1, page_count( 0, 5, 28));
     BOOST_TEST_EQUAL(1, page_count( 1, 5, 28));
     // Just a trivial sanity test.
     BOOST_TEST_EQUAL(1, page_count(17, 5, 28));
@@ -171,9 +172,9 @@ void test_page_count()
 
     // Test preconditions.
 
-    // No data rows.
+    // Negative number of data rows.
     BOOST_TEST_THROW
-        (page_count(0, 1, 1)
+        (page_count(-1, 1, 1)
         ,std::runtime_error
         ,lmi_test::what_regex("^Assertion.*failed")
         );